Universal ring jaws

ABSTRACT

A method for chucking work in lathes is disclosed. Each of a plurality of segmented circular backing plates, which backing plates are interconnected by a plurality of guides, are attached to one of the jaw mountings of the lathe. A segment of a segmented ring is secured to each of the segmented backing plates and machined to receive a work piece. The backing plates are inwardly radially displaced to permit mounting of the work piece upon the segmented ring and then outwardly radially displaced to draw the segmented ring against the work piece. Where the work piece is mounted externally rather than internally, the above mounting process is reversed. The guides interconnecting the backing plates are tightened to rigidly secure the backing plates to one another and, in combination with the segmented ring, form a solid mounting for the work piece. The work piece may now be machined without any danger of misalignment, wobble, or flutter of the mounting assembly.

Apr. 2, 1974 UNIVERSAL RING JAWS [76] lnventor: Vernon B. Bailiff, 3608 w. Harrnont Dr., Phoenix, Ariz. 85021 Filed: May 16, 1973 Appl. No.: 360,808

Related US. Application Data Division of Ser. No. 185,972, Oct. 4, 1971, Pat No. 3,747,945.

References Cited UNITED STATES PATENTS 2/1960 Borsetti 279/1 SJ 2,994,539 8/1961 Farnsworth..... 279/1 SJ 2,398,564 4/1946 Stoner 29/445 X FOREIGN PATENTS OR APPLICATIONS 104,488 3/1917 Great Britain 279/123 Primary ExaminerLeonidas Vlachos Attorney, Agent, or Firm-Cahill, Sutton & Thomas [57] ABSTRACT A method for chucking work in lathes is disclosed. Each of a plurality of segmented circular backing plates, which backing plates are interconnected by a plurality of guides, are attached to one-of the jaw mountings of the lathe. A segment of a segmented ring is secured to each of the segmented backing plates and machined to receive a work piece. The backing plates are inwardly radially displaced to permit mounting of the work piece upon the segmented ring and then outwardly radially displaced to draw the segmented ring against the work piece. Where the work piece is mounted externally rather than internally, the above mounting process is reversed. The guides interconnecting the backing plates are tightened to rigidly secure the backing plates to one another and, in combination with the segmented ring, form a solid mounting for the work piece. The work piece may now be machined without any danger of misalignment, wobble, or flutter of the mounting assembly.

4 Claims, 5 Drawing Figures PAIENIEMR 2 m4 SHEET 1 [IF 2 a I U g r i PATENTEDAPR 2 Ian I 3.800 402 SHEET 2 0F 2 1 UNIVERSAL RING JAWS This is a divisional application of patent application Ser. No. 185,972, filed on Oct. 4, 1971, entitled, Universal Ring Jaws, now US. Pat. No. 3,747,945.

This invention relates to devices useful in expansively or contractively attaching work pieces to lathes.

In the prior art, various methods have been used to attach work pieces to lathes. Initially, a slit collet was used to directly hold the work piece and on ocassion it had to be machined to fit. This machining operation was expensive as the collets were of hardened material. Once machined, the collets were adapted to fit only work pieces of that particular diameter, unless further enlarged. After the collets had been machined to the point where the metal remaining in the periphery was insufficient to form the chucking jaws for the work piece, the collets had to be discarded. The attendant replacement costs further increased the costs of the machining operation.

To overcome the above-described collet machining and replacement costs, pie-shaped chuck jaws of soft material, such as sluminum, were bolted onto the respective slit portions of the collet. With this configuration, the aluminum chuck jaws,- rather than the collet, were machined to fit and hold the work piece. This method saved the cost of machining the hardened collets and their replacement, but inroduced further and different problems. The aluminum chuck jaws were of uniform thickness from their center to their periphery. To hold a work piece, the chuck jaws had to be machined either from the center outwardly or from the periphery inwardly, depending on whether the work piece was to be held by expanding against an inside diameter or contracting against an outside diameter of the work piece. As with the prior machining of the collets, once the chuck jaws have been machined, further utility was predicated on future work pieces being of lesser or greater diameter, depending on whether the work piece is held contractively or expansively. In many situations, the machining operation in preparing the chuck jaws removed a large portion of the material and thus severely limited its future usefulness. For dish-shaped work pieces, where the dished portion is to be imbedded within the chuck jaws, a large amount of material at the center of the chuck jaws must be removed. The setting up time required for so preparing the chuck jaws is expensive and limits the future usefulness of the chuck jaws.

In situations requiring the machining of hard work pieces, such as Hastalloy or Waspalloy, the chuck jaws must be tightened to a greater-than-normal extent to retain the work piece on the chuck jaws in a non-sliding relationship. This additional tightening will tend to bend or distort the aluminum chuck jaws due to the leverage arm between the collet attachment and the point of attaching the work piece. Distortion of the chuck jaws in a plane normal to the axis will also misalign the groove or shoulder machined into the chuck jaws for securing the work piece. Misalignment of the groove or shoulder will cause the work piece not to seat properly. This result is wholly unacceptable in situations requiring close tolerance work.

The use of soft aluminum chuck jaws secured between :1 collet and the work piece presents a still further problem. The axial distance between the collet member and the point of contact between the work piece and the cutting tool may be great enough to permit the aluminum chuck jaws to bend or distort under pressure of the cutting tool. This problem becomes more prevalent as the chuck jaws become thinned after repeated machining. Any distortion caused thereby will affect the accuracy with which the work piece may be machined.

It is therefore a primary object of the present invention to provide a rigid support for machining work pieces.

Another object of the present invention is to provide an easily machinable segmented ring jaw for supporting a work piece.

Another object of the present invention is to provide a segmented ring jaw requiring a minimum amount of machining to attach a work piece thereto.

Another object of the present invention is to provide a planarly rigid backing plate for supporting segmented ring jaws.

Still another object of the present invention is to provide a plurality of different sized segmented ring jaws attachable to a single planar backing plate.

These and other objects of the present invention will become apparent to those skilled in the art as the description thereof proceeds.

The present invention may be described with more specificity and clarity with reference to the following figures, in which:

FIG. 1 illustrates a lathe incorporating the teachings of the present invention.

FIG. 2 illustrates a cross-sectional view of the present invention.

FIG. 3 illustrates the backing plate of the present invention.

FIG. 4 illustrates a cross section of the backing plate shown in FIG. 3.

FIG. 5 illustrates a pair of different sized ring jaws of the present invention.

Referring to FIG. 1, there is shown a lathe housing 1 having a lathe chuck 2 extending therefrom. Conventional lathes and lathe chucks are well understood in the art and the following description will only touch upon those aspects directly co-operating with the present invention. The lathe chuck 2 has a plurality of jaw mountings 3 extending radially and movable radially toward and away from the axis of rotation of the lathe chuck 2. The radial inward and outward movement of the jaw mountings 3 is controlled by a gearing mechanism which is substantially conventional in all lathe chucks 2 and is controlled by a hand wrench fitting in the wrench receiving socket 4.

In the preferred embodiment of the invention, the backing plate 5 is constructed of three segregable pieshaped planar members 5a, 5b, and 50. Each of the members 5a, 5b, and 50 includes a plurality of holes generally radially oriented with respect to each other and generally centered between the radial edges of the member. Each of the members includes an integral assembly 6 which interfaces with the respective jaw mounting in a tongue and groove relationship. Two holes 13, 14 in member 5a are aligned with two threaded holes l7, 18 within jaw mounting 3. Bolts 19, 20 are countersunk in holes 13, 14 and extend therethrough, and are screwed into holes l7, 18 of jaw mounting 3 to firmly secure each member (5a, 5b, SC) to its respective jaw mounting 3. In addition, a key 7 of hardened material is attached by bolt 8 to the respective member in a channel 9 of assembly 6 and engages channel 10 in jaw mounting 3 to provide not only a fn'ction fit by tightening bolts 19 and 20 but also interlocking physical constraints to prevent any lateral or rotational movement of piece 10 with respect to jaw mounting 3.

Each of the members (5a, 5b, 5c) of backing plate 5 is attachable to the adjacent member through a planar slotted rectangular guide 21, 22, 23. These guides 21, 22, 23 are attached to their respective member 5a, 5b, 50 by bolts, such as bolts 37, 38 extending through the slotted portion and threaded into holes, such as holes 39, 40, in the member. The surface of each member 5a, 5b, 5c adjacent the guide 21, 22, 23 is planar with the guide to provide a firm seating Thus, on tightening the respective bolts to secure the guides 21, 22, 23 to their respective members 5a, 5b, 50, a rigid unitary planar structure is formed. By loosening the bolts, the members 5a, 5b, 56 may be moved radially as the slots 24, 25, 26 of the guides 21, 22, 23 compensate for the change in circumferential distance between the bolts of adjacent members 5a, 5b, 50. Thus, the members may be moved radially inwardly until the sides of the members contact one another and radially outwardly to the extent permitted by the slots 24, 25, 26 in the guides 21, 22, 23. At these extremes, or at any point therebetween, the bolts may be tightened to secure the guides 21, 22, 23 with their respective members and establish a rigid unitary structure. The use of high strength steel for the components of the backing plate 5 and the guides 21, 22, 23 further adds to the rigidity of the unitary structure. If desired, the guides 21, 22, 23 may be keyed to their respective members 5a, 5b, 50 by a tongue and groove arrangement (not shown). With this arrangement, the members 5a, 5b, and 50 will be forced to move radially by equal amounts and it will augment the action of the jaw mountings 3.

ln FIGS. 1, 2, and 5, there are shown various views of the ring jaws 27 to be used with the backing plate 5. The ring jaws 27 may bemanufactured from aluminum or other easily machinable metal. If desired, they may be manufactured as segments 28, 29, 30 (see FIG. 5) of a ring or as a ring subsequently divided into segments. The width, depth, and radii of the ring jaws 27 may be varied, although the segments may be most useful if they have a radial cross section of generally rectangular shape. FIG. 5 illustrates two differentially sized ring jaws that may be mounted on backing plate 5. Each of the members 5a, 5b, and St has disposed therein at least'two threaded holes 31, 32, each disposed along and centered on an imaginary circle of lesser diameter than the diameter of the backing plate 5.

Similarly, a segmented ring jaw 27, having a mean radius equal to the radius of the imaginary circle, has disposed therein a plurality of holes 33, 34 centered on the imaginary circle and aligned with the threaded holes (such as 31, 32) in the backing plate 5. Each of the segments 28, 29, 30 of the ring jaw 27 is affixed to one of the members 5a, 5b, 5c of the backing plate 5 by bolts (such as 35, 36) inserted into the holes 33, 34 in the segment 28 and engaging the respective threaded hole (such as 31, 32) in the respective member. In this manner, the segmented ring jaw 27 is attached to the backing plate 5. For best results, the bolts 35, 36 should be countersunk in the segments and the shafts of the bolts should be in close tolerance with their respective holes to provide a physical as well as a frictional constraint against movement therebetween.

In order to provide a plurality of different sized ring jaws 27 as shown in FIG. 5 for a backing plate 5, a plurality of sets of holes centered on a plurality of different diametered imaginary circles may be disposed in the backing plate 5. Each of these sets of holes would correspond with the holes in a plurality of different diametered ring jaws 27. Thereby, only one backing plate 5 would be needed to mount any segmented ring jaw 27 from a size equivalent in diameter to the inward point of the backing plate members to a size equivalent in diameter to the circumference of the backing plate.

The overall functional aspect of the above-described ring jaws 27 is similar to the fiinctions obtained from the prior art chuck jaws in terms of their role in holding the work piece to be machined. However, there are a myriad of advantages to be obtained from the ring jaws 27 that were not available from the devices of the prior art. These advantages will become obvious from the following discussion of the operation of the instant invention.

An advantage of the invention is that of the feasibility with which the invention may be used on any sized lathe from the smallest to the largest. The diametrical size of the work piece to be worked on a lathe is limited only by the size of the backing plate 5 that can be mounted on the chuck mountings 3. The size of the backing plate 5 is limited by the lathe structure radially closest to the axis of rotation and which would interfere with the rotation of the backing plate 5. Once the largest possible size backing plate 5 has been determined, it may be mounted on the jaw mountings 3. As it represents the largest size work piece that can be machined on that particular lathe, there is no need to ever remove it, except for reasons of maintenance. This represents a substantial time and labor savings over prior known chuck jaws as the latter were continually being used up in terms of continually adapting them to receive new different sized work pieces. An ancillary advantage of the invention is that of extending the life of the mechanism securing the backing plate 5, formerly the chuck jaws, to the rotating shaft of the lathe as they must be loosened and tightened less often.

After a backing plate 5 has been selected and mounted on mountings 3, a segmented ring jaw 27 is selected to be attached thereto. The selection of the size of the ring jaw 27 should be controlled by the following criteria. The ring jaw 27 should be selected so that either its inside or outside diameter most closely approaches the diameter of the work piece portion which is to be mounted thereon. In this manner, the least amount of material needs to be removed from the ring jaw 27 in preparing it to accept the work piece. This presents a substantial setting up time savings and a substantial economy in discarded material costs.

After selecting the appropriate sized ring jaw 27, each segment 28, 29, 30 is mounted on a backing plate member 5a, 5b, 5c and secured thereto by bolts, such as 35, 36. The ring jaw 27 is then machined to provide the requisite seating for the work piece. On completion thereof, the guides 21, 22, 23 are loosened and the backing plate members 5a, 5b, 5c are drawn inwardly slightly or extended outwardly slightly, depending on whether the work piece is fitted onto the ring jaws in an inside or outside diameter configuration by turning socket 4. This permits the work piece to be fitted onto the ring jaw 27. The work piece is then secured to the ring jaw 27 by reversely moving the backing plate members 5a, 5b, 50 until a snug fit is obtained between the ring jaw 27 and the work piece. The guides 21, 22, 23 are tightened by their respective bolts to securely tie the backing plate members 50, 5b, SC to one another and thereby form a rigid unitary mounting for the work pice. The work piece may now be machined. To remove the work piece, the guides 21, 22, 23 are loosened and the members 5a, 5b, and 5c are moved radially to disengage the ring jaw 27 from the work piece.

In situations where the work piece is of very hard and difficult to machine metal, the radial force exerted by the jaws securing the work piece has to be substantial to provide the requisite frictional force to prevent the work piece from rotating under the forces of the cutting tool. This situation establishes substantial counter forces that are axially displaced, causing possible deformation of the jaws, such as the aluminum pie jaws used in the prior art. Any such deformation will misalign the seating machined in the jaws and subject the work piece to uneven forces. Accurate high tolerance of the work piece is then impossible. The problem became even more severe after the pie-shaped chuck jaws were thinned due to repeated machining to fit various sized work pieces thereon.

In the present invention, the above-described distortion is avoided for all practical purposes. The design of the backing plate 5 is such that it may be made of high strength steel and by use of the guides 21, 22, 23 presents a rigid planar unitary structure not subject to deformation under any expected loads. The ring jaws 27, though usually made from aluminum and less rigid than steel, are securely fastened to the backing plate members 5a, 5b, 5c. The steel bolts 35, 36, being in close tolerance with the holes 33, 34 in the segments 28, 29, 30,

lends rigidity to the jaw 27. The axial distance between the heads of the bolts and the work piece is verysmall and thus presents a minimum leverage arm through which the previously discussed counter forces may act. Thus, the possibility of the ring jaw 27 securing the work piece to a lathe, as described in the instant invention, being subjected to distortion is at a minimum. To reduce the possibility to practically zero for even ultrahard work pieces, the ring jaw 27 may be made of steel rather than aluminum. For extended runs, two sets of ring jaws arranged in an overlapping relationship may be used. Fantastic rigidity is obtained thereby, yet only one set of ring jaws need to be machined and the second set may be used for other machining operations later on. The expense of machining steel ring jaws is also avoided.

In many applications, dish-shaped work pieces must be machined. The instant invention admirably lends itself to this situation. Here, a ring jaw size is selected which will engage the periphery of the work piece at or close to the ring jaw 27 inner diameter. Thus, the set-up time previously required to machine out pie-shaped jaws to provide a recess for the dished portion is completely obviated. This represents a substantial savings in the cost of the machinists time, lathe time, and aluminum.

In some machining operations, there is a requirement to work a flange at the inner diameter of the work piece. In the previously used pie-shaped aluminum chuck jaws, the jaws had to be machined to provide a recess to permit the cutting tool to be inserted therein before the work piece could be machined. This operation was a substantial portion of the set-up time required and added to the overall cost of the machining process. With the instant invention, the above-required set-up time is wholly avoided as the ring jaw 27 automatically provides a sufficient recess to insert a cutting tool therein.

The cost of either pie-shaped chuck jaws or ring jaws is basically on a dollar per pound basis. Obviously, the less weight that must be machined away to fit a work piece onto the jaws the lower is the cost of the machining operation. With the use of the ring jaw 27, the excess material that must be machined away is at a minimum and substantially reduces the costs of any machining operation. In example, the cost comparisons obtained over a period of time have been in the neighborhood of 10 to one.

I claim:

1. A method of mounting a work piece on the jaw mountings of a lathe comprising the steps of:

connecting each member of a segmented circular backing plate to one of the jaw mountings; attaching a segment of a segmented ring jaw to each one of said members;

machining said segmented ring jaw to receive a work piece;

fitting the work piece to said segmented ring jaw;

radially displacing said members of said backing plate to draw said ring jaw against the work piece; and

tightening each of a plurality of guides bridging said adjacent members, whereby the work piece is securely mounted on the lathe.

2. The method of claim 1, wherein the step of attaching each segment to one of said members includes the steps of: inserting a plurality of bolts into countersunk holes within each of said segments, and securing the bolts to said members.

3. The method of claim 2, wherein said guides include a slot disposed therein for receiving the shaft of a bolt and each said member includes at least two threaded holes for receiving bolts, the step of tightening includes the steps of:

inserting bolts through said slotted guide, and

threadedly securing each of said bolts to adjacent ones of said members.

4. The method of claim 3, including the step of sliding the slotted guides with respect to the bolt shafts during the step of radially displacing said members. 

1. A method of mounting a work piece on the jaw mountings of a lathe comprising the steps of: connecting each member of a segmented circular backing plate to one of the jaw mountings; attaching a segment of a segmented ring jaw to each one of said members; machining said segmented ring jaw to receive a work piece; fitting the work piece to said segmented ring jaw; radially displacing said members of said backing plate to draw said ring jaw against the work piece; and tightening each of a plurality of guides bridging said adjacent members, whereby the work piece is securely mounted on the lathe.
 2. The method of claim 1, wherein the step of attaching each segment to one of said members includes the steps of: inserting a plurality of bolts into countersunk holes within each of said segments, and securing the bolts to said members.
 3. The method of claim 2, wherein said guides include a slot disposed therein for receiving the shaft of a bolt and each said member includes at least two threaded holes for receiving bolts, the step of tightening includes the steps of: inserting bolts through said slotted guide, and threadedly securing each of said bolts to adjacent ones of said members.
 4. The method of claim 3, including the step of sliding the slotted guides with respect to the bolt shafts during the step of radially displacing said members. 